With authorities concluding from new satellite data that Malaysia Airlines Flight 370 went down in the Indian Ocean, the focus is now shifting to finding cockpit recording devices and any debris that might shed light on what happened to the Boeing 777-200.

The slow trickle of information continues to leave unanswered whether the tragedy was a mechanical failure of the aircraft itself, or a willful act of someone who took the plane on a new course until it ran out of fuel.

“I still think this was some illegal criminal act that occurred on the airplane, and not an airplane issue,” said Scott Hamilton, president of Leeham Co. LLC, a Seattle-area aerospace consultancy. “What the criminal act might be, I have no way to know.”

In a brief televised statement, Malaysian Prime Minister Najib Razak said early Monday that new satellite information indicates the aircraft’s flight last position was in the middle of the Indian Ocean, west of Perth.

“This is a remote location, far from any possible landing sites,” he said. “It is therefore, with deep sadness and regret, that I must inform you that according to this new data Flight MH 370 ended in the southern Indian Ocean.”

Boeing sent out a brief statement Monday morning:

“Boeing is saddened by today’s announcement by the prime minister of Malaysia regarding Malaysia Airlines Flight 370. Our thoughts and deepest sympathies continue to be with the families and loved ones of those aboard. Boeing continues to serve as a technical adviser to the U.S. National Transportation Board.”

Boeing spokesman Wilson Chow declined to elaborate on whether Boeing is sending more people to the region of the aircraft’s likely descent into the ocean.

“We’re not detailing what the team’s expertise is or what they’re doing,” he said. “We’re not going to be able to comment on that question.”

“It is with deep sadness that Malaysia Airlines earlier this evening had to confirm to the families of those on board Flight MH370 that it must now be assumed the flight had been lost....When Malaysia Airlines receives approval from the investigating authorities, arrangements will be made to bring the families to the recovery area and until that time, we will continue to support the ongoing investigation.”

Authorities will now focus on recovering the aircraft’s flight data recorder and cockpit voice recorders, which “should provide a wealth of information,” Hamilton said.

A limitation is that the cockpit voice recorder contains only the last two hours of conversations, and that could be limited to the last 30 minutes according to Malaysian law, Hamilton said.

While there won’t be recordings of the crucial period after the aircraft left the Malaysian capital of Kuala Lumpur and then changed course, the final minutes of the aircraft’s flight should be telling, he said.

Assuming the aircraft did put down in the ocean, it almost assuredly broke up on impact. If any parts of the fuselage, wings or engines are found, these may also yield clues about what caused the incident.

But since indications are that Flight 370’s diversion and subsequent end was a human act, and that the aircraft was performing as designed, the most crucial evidence will come from the cockpit and data recorders.

Those have a battery life of about a month, powering the sonar beacons that make them findable underwater.